'\" et
.TH WCSTOMBS "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
wcstombs
\(em convert a wide-character string to a character string
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>
.P
size_t wcstombs(char *restrict \fIs\fP, const wchar_t *restrict \fIpwcs\fP,
    size_t \fIn\fP);
.fi
.SH DESCRIPTION
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
The
\fIwcstombs\fR()
function shall convert the sequence of wide-character codes that are
in the array pointed to by
.IR pwcs
into a sequence of characters that begins in the initial shift state
and store these characters into the array pointed to by
.IR s ,
stopping if a character would exceed the limit of
.IR n
total bytes or if a null byte is stored. Each wide-character code
shall be converted as if by a call to
\fIwctomb\fR(),
except that the shift state of
\fIwctomb\fR()
shall not be affected.
.P
The behavior of this function shall be affected by the
.IR LC_CTYPE
category of the current locale.
.P
No more than
.IR n
bytes shall be modified in the array pointed to by
.IR s .
If copying takes place between objects that overlap, the behavior is
undefined.
If
.IR s
is a null pointer,
\fIwcstombs\fR()
shall return the length required to convert the entire array
regardless of the value of
.IR n ,
but no values are stored.
.SH "RETURN VALUE"
If a wide-character code is encountered that does not correspond to a
valid character (of one or more bytes each),
\fIwcstombs\fR()
shall return (\fBsize_t\fP)\-1. Otherwise,
\fIwcstombs\fR()
shall return the number of bytes stored in the character array, not
including any terminating null byte. The array shall not be
null-terminated if the value returned is
.IR n .
.SH ERRORS
The
\fIwcstombs\fR()
function shall fail if:
.TP
.BR EILSEQ
A wide-character code does not correspond to a valid character.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fImblen\fR\^(\|)",
.IR "\fImbtowc\fR\^(\|)",
.IR "\fImbstowcs\fR\^(\|)",
.IR "\fIwctomb\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<stdlib.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
